Is it possible to add a Handling Fee to my shipments?

I want to offer free Domestic shipping for purchases over a certain amount. How do I do that?

eShop supports free shipping for purchases of a given total price under Settings->eShop->Discounts. However, you cannot specify the location without installing another of UseStrict's plugins:
eshop-free-shipping-locations-lite or eshop-free-shipping-locations-pro (coming soon). The Lite version checks the client's state against the state the admin specified as being eligible for free shipping - regardless of the amount spent.
The Pro version gives you more flexibility:

Select multiple countries/states

Specify whether the locations override the price or if both price and location are taken into consideration